A key question in climate change models is how much carbon is sequestered by ecosystems; researchers have attempted to answer this question by modeling fluxes globally or looking at tree growth and other clues to carbon storage. Now a worldwide network of 70 or so towers already running or about to come online will soon churn out a stream of data on how much COis socked away in various soil and plant types. That information should, over the long haul, help refine models of global warming as greenhouse gases continue to build up in the atmosphere and could potentially be used to help enforce the Kyoto treaty.